LEP SENSITIVITIES TO SPONTANEOUS R-PARITY VIOLATING SIGNALS

We illustrate the sensitivities of LEP experiments to leptonic signals associated to models where supersymmetry (SUSY) is realized with spon taneous breaking of R-parity. We focus on missing transverse momentum plus acoplanar muon events (p(T)' + mu(+) mu(-)) arising from lightest neutralino single production chi nu as well as pair production chi ch i, followed by chi decays, where chi denotes the lightest neutralino. We show that the integrated luminosity achieved at LEP already starts probing the basic parameters of the theory. We discuss the significanc e of these constraints for the simplest spontaneous R-parity breaking models and their relevance for future searches of SUSY particles.